It is well known that environmental aggressors such as UV radiation, environmental pollution, environmental toxins, physiological stress, and the natural process of aging can be very detrimental to skin. The skin on the face is made up of keratinocytes, fibroblasts, melanocytes, T-cells and so on. Environmental aggressors cause damage to DNA of skin cells and affects the cellular circadian rhythm in general. The body's natural circadian rhythms are synchronized such that during exposure to environmental aggressors—usually during daylight hours—certain genes in the cells are activated to produce proteins that protect the cells against damage.
Genes associated with natural bodily circadian rhythms have been identified and include the clock (Circadian Locomotor Output Cycles Kaput) gene and the per1 (Period Homolog 1) gene, both of which encode proteins (CLK and PER1) that regulate circadian rhythms. Clock and per1 genes are also present in skin cells. The induction of per1 gene expression initiates a program of cellular activity that is associated with biological processes that take place at night (e.g. repair). It is known that skin cells exposed to environmental aggressors will often exhibit decreased, irregular, or asynchronous clock or per1 gene expression. This in turn causes disruption of normal circadian rhythm in the exposed skin cells. Over a prolonged period of time disruption of normal cellular circadian rhythm and synchronicity can accelerate the natural aging process of skin which leads to wrinkles, fine lines, skin laxity, uneven pigmentation, age spots, mottling, and the like.
For this reason it is very advantageous to maintain natural cellular circadian rhythm to the greatest extent possible. To date, the only known mechanisms for synchronizing skin cells are to (1) starve the cells for an extended period of time by removing nutrients and energy sources, and then suddenly resupply the nutrients; or (2) treating the skin cells with a peptide having the C.T.F.A. name Tripeptide-32. The practical difficulties in starving skin cells not in culture are obvious. In addition, the ingredient known to have this activity is expensive.
It has been discovered that ingredients containing at least one linoleic acid moiety are an effective stimulator of per1 gene expression in skin cells. The ability to increase per1 gene expression in skin cells means that skin cells with irregular or decreased synchronicity will become synchronized (e.g. all cells exhibit same level of per1 gene expression at the same time). When skin cells are synchronized, treatment of the skin cells with active ingredients that repair cellular damage are the most effective. It is most beneficial to treat skin cells to increase per1 gene expression and thereby cause the treated cells to be synchronized so that the active ingredients in skin treatment products may be optimally beneficial to the skin cells. In one most preferred embodiment of the invention the skin cells are treated with an ingredient containing at least one polyunsaturated omega-6 fatty acid to increase per1 gene expression and synchronicity at night prior to retiring.